ExpectedAttributeValue (AWS SDK for Java

java.lang.Object
- com.amazonaws.services.dynamodbv2.model.ExpectedAttributeValue

All Implemented Interfaces:

Serializable
```
public class ExpectedAttributeValue
extends Object
implements Serializable
```
Represents an attribute value used with conditional DeleteItem , PutItem or UpdateItem operations. DynamoDB will check to see if the attribute value already exists; or if the attribute exists and has a particular value before updating it.

See Also:
Serialized Form

Constructor Summary

Constructors
Constructor and Description
`ExpectedAttributeValue()` Default constructor for a new ExpectedAttributeValue object.
`ExpectedAttributeValue(AttributeValue value)` Constructs a new ExpectedAttributeValue object.
`ExpectedAttributeValue(Boolean exists)` Constructs a new ExpectedAttributeValue object.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object obj)`
`Boolean`	`getExists()` Causes DynamoDB to evaluate the value before attempting a conditional operation:
`AttributeValue`	`getValue()` Represents the data for an attribute.
`int`	`hashCode()`
`Boolean`	`isExists()` Causes DynamoDB to evaluate the value before attempting a conditional operation:
`void`	`setExists(Boolean exists)` Causes DynamoDB to evaluate the value before attempting a conditional operation:
`void`	`setValue(AttributeValue value)` Represents the data for an attribute.
`String`	`toString()` Returns a string representation of this object; useful for testing and debugging.
`ExpectedAttributeValue`	`withExists(Boolean exists)` Causes DynamoDB to evaluate the value before attempting a conditional operation:
`ExpectedAttributeValue`	`withValue(AttributeValue value)` Represents the data for an attribute.

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - ExpectedAttributeValue
```
public ExpectedAttributeValue()
```
    Default constructor for a new ExpectedAttributeValue object. Callers should use the setter or fluent setter (with...) methods to initialize this object after creating it.
  - ExpectedAttributeValue
```
public ExpectedAttributeValue(AttributeValue value)
```
    Constructs a new ExpectedAttributeValue object. Callers should use the setter or fluent setter (with...) methods to initialize any additional object members.
    
    Parameters:
    value - Represents the data for an attribute. You can set one, and only one, of the elements.
  - ExpectedAttributeValue
```
public ExpectedAttributeValue(Boolean exists)
```
    Constructs a new ExpectedAttributeValue object. Callers should use the setter or fluent setter (with...) methods to initialize any additional object members.
    Parameters:
    exists - Causes DynamoDB to evaluate the value before attempting a conditional operation:
    
    If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    
    If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    
    Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    
    Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
- Method Detail
  - getValue
```
public AttributeValue getValue()
```
    Represents the data for an attribute. You can set one, and only one, of the elements.
    
    Returns:
    Represents the data for an attribute. You can set one, and only one, of the elements.
  - setValue
```
public void setValue(AttributeValue value)
```
    Represents the data for an attribute. You can set one, and only one, of the elements.
    
    Parameters:
    value - Represents the data for an attribute. You can set one, and only one, of the elements.
  - withValue
```
public ExpectedAttributeValue withValue(AttributeValue value)
```
    Represents the data for an attribute. You can set one, and only one, of the elements.
    Returns a reference to this object so that method calls can be chained together.
    
    Parameters:
    value - Represents the data for an attribute. You can set one, and only one, of the elements.
    
    Returns:
    A reference to this updated object so that method calls can be chained together.
  - isExists
```
public Boolean isExists()
```
    Causes DynamoDB to evaluate the value before attempting a conditional operation:
    - If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    - If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    - Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    - Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
    Returns:
    Causes DynamoDB to evaluate the value before attempting a conditional operation:
    
    If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    
    If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    
    Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    
    Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
  - setExists
```
public void setExists(Boolean exists)
```
    Causes DynamoDB to evaluate the value before attempting a conditional operation:
    - If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    - If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    - Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    - Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
    Parameters:
    exists - Causes DynamoDB to evaluate the value before attempting a conditional operation:
    
    If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    
    If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    
    Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    
    Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
  - withExists
```
public ExpectedAttributeValue withExists(Boolean exists)
```
    Causes DynamoDB to evaluate the value before attempting a conditional operation:
    - If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    - If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    - Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    - Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
    Returns a reference to this object so that method calls can be chained together.
    Parameters:
    exists - Causes DynamoDB to evaluate the value before attempting a conditional operation:
    
    If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    
    If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    
    Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    
    Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
    Returns:
    A reference to this updated object so that method calls can be chained together.
  - getExists
```
public Boolean getExists()
```
    Causes DynamoDB to evaluate the value before attempting a conditional operation:
    - If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    - If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    - Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    - Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
    Returns:
    Causes DynamoDB to evaluate the value before attempting a conditional operation:
    
    If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
    
    If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
    
    The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.
    DynamoDB returns a ValidationException if:
    
    Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
    
    Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)
    
    If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.
  - toString
```
public String toString()
```
    Returns a string representation of this object; useful for testing and debugging.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    A string representation of this object.
    See Also:
    Object.toString()
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object

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Class ExpectedAttributeValue

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ExpectedAttributeValue

ExpectedAttributeValue

ExpectedAttributeValue

Method Detail

getValue

setValue

withValue

isExists

setExists

withExists

getExists

toString

hashCode

equals